32 bit or 64 bit (OS or CPU)

abhishekrahel · 05-12-2008, 09:27 PM

Hi All

Could anyone help me in how to find installed operating system linux is 32 bit or 64 bit and how to find CPU is 32 bit or 64 bit ?

i am in confusion regarding this.
What i came to know through the below link:->
http://www.cyberciti.biz/faq/linux-h...64-bit-or-not/

that we can find out about CPU is 32 bit or 64 bit.

But i am in confusion about how to confirm Linux is 32 bit or 64 bit ?

Waiting for response.

Thanks in advance.

johnsfine · 05-13-2008, 04:52 AM

I assume you're asking about an x86 system.

uname -a will tell you if the Linux kernel is 64 bit.

If the output includes x86_64 then the kernel is 64 bit, which means the CPU must be 64 bit.

If there is no X86_64, there should be something like 686 or 486 there to say what 32 bit CPU the kernel was built for. If the kernel is 32 bit, the CPU might still be 64 bit. Try

grep flags /proc/cpuinfo

That should print a long list of cpu flags. If one of those is lm then the CPU is 64 bit.

abhishekrahel · 05-14-2008, 02:05 PM

Quote:

Originally Posted by johnsfine

I assume you're asking about an x86 system.

uname -a will tell you if the Linux kernel is 64 bit.

If the output includes x86_64 then the kernel is 64 bit, which means the CPU must be 64 bit.

If there is no X86_64, there should be something like 686 or 486 there to say what 32 bit CPU the kernel was built for. If the kernel is 32 bit, the CPU might still be 64 bit. Try

grep flags /proc/cpuinfo

That should print a long list of cpu flags. If one of those is lm then the CPU is 64 bit.

Thanks johnsfine for the response.

In other words:->
So now i am having a small doubt that if the output of grep flags /proc/cpuinfo contains lm it means definitely CPU is 64 bit and can handle
both 32 and 64 bit kernel and if the output does not contains lm means CPU is definitely 32 bit and can handle 32 bit kernel and cant handle 64 bit kernel or can handle 64 bit kernel also.

And if the output of uname -a includes x86_64 then the kernel is definitely 64 bit.
And if the output does not include x86_64 means definitely the kernel is 32 bit(contains others like i686 i686 i386 GNU/Linux).

Thanks
Abhishek Rahel.

onebuck · 05-14-2008, 10:45 PM

Hi,

If you do a 'most /proc/cpuinfo';

Code:

processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 67
model name      : AMD Athlon(tm) 64 X2 Dual Core Processor 3800+
stepping        : 3
cpu MHz         : 2009.178
cache size      : 512 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 2
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov$
bogomips        : 4022.19
clflush size    : 64

processor       : 1
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 67
model name      : AMD Athlon(tm) 64 X2 Dual Core Processor 3800+
stepping        : 3
cpu MHz         : 2009.178
cache size      : 512 KB
physical id     : 0
siblings        : 2
core id         : 1
cpu cores       : 2
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov$
bogomips        : 4018.27
clflush size    : 64

What part don't you understand? If you do a 'uname -a';

Code:

 uname -a
Linux amd64 2.6.24.5-smp #2 SMP Wed Apr 30 13:41:38 CDT 2008 i686 AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ AuthenticAMD GNU/Linux

shows the kernel information with the processor information.

abhishekrahel · 05-16-2008, 05:10 PM

Quote:

Originally Posted by onebuck

Hi,

If you do a 'most /proc/cpuinfo';

Code:

processor       : 0
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 67
model name      : AMD Athlon(tm) 64 X2 Dual Core Processor 3800+
stepping        : 3
cpu MHz         : 2009.178
cache size      : 512 KB
physical id     : 0
siblings        : 2
core id         : 0
cpu cores       : 2
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov$
bogomips        : 4022.19
clflush size    : 64

processor       : 1
vendor_id       : AuthenticAMD
cpu family      : 15
model           : 67
model name      : AMD Athlon(tm) 64 X2 Dual Core Processor 3800+
stepping        : 3
cpu MHz         : 2009.178
cache size      : 512 KB
physical id     : 0
siblings        : 2
core id         : 1
cpu cores       : 2
fdiv_bug        : no
hlt_bug         : no
f00f_bug        : no
coma_bug        : no
fpu             : yes
fpu_exception   : yes
cpuid level     : 1
wp              : yes
flags           : fpu vme de pse tsc msr pae mce cx8 apic sep mtrr pge mca cmov$
bogomips        : 4018.27
clflush size    : 64

What part don't you understand? If you do a 'uname -a';

Code:

 uname -a
Linux amd64 2.6.24.5-smp #2 SMP Wed Apr 30 13:41:38 CDT 2008 i686 AMD Athlon(tm) 64 X2 Dual Core Processor 3800+ AuthenticAMD GNU/Linux

shows the kernel information with the processor information.

Hi
I have recently bought a notebook Vostro 1000 (AMD Turion 64*2)and installed FC 7 on that.

So
grep flags /proc/cpuinfo is :->

flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8legacy 3dnowprefetch ts fid vid ttp tm stc 100mhzsteps

flags : fpu vme de pse tsc msr pae mce cx8 apic mtrr pge mca cmov pat pse36 clflush mmx fxsr sse sse2 ht syscall nx mmxext fxsr_opt rdtscp lm 3dnowext 3dnow pni cx16 lahf_lm cmp_legacy svm extapic cr8legacy 3dnowprefetch ts fid vid ttp tm stc 100mhzsteps

And uname -a is :->

Linux RAHEL 2.6.21-1.3194.fc7 #1 SMP Wed May 23 22:35:01 EDT 2007 i686 athlon i386 GNU/Linux

And according to what I got that CPU is 64 bit and kernel is 32 bit.

But if i do getconf LONG_BIT
I got 32
So i am confused i should rely on getconf or on lm in flags, about CPU(64 bit or 32 bit)

and what the meaning of both i686 and i386 in the output of uname -a,
or simply i should understand that as it does not contains x86_64(as it is) kernel installed is 32 bit.

So Could you please guide me to understand this.

Thanks.

johnsfine · 05-16-2008, 06:56 PM

Quote:

Originally Posted by abhishekrahel

according to what I got that CPU is 64 bit and kernel is 32 bit.

Correct.

Quote:

But if i do getconf LONG_BIT
I got 32
So i am confused i should rely on getconf or on lm in flags, about CPU(64 bit or 32 bit)

I did a couple searches to try to find the meaning of LONG_BIT in getconf and failed to find it. Maybe some expert will tell us both.

But I know the meaning of lm in flags. Your CPU is 64 bit.

Quote:

and what the meaning of both i686 and i386 in the output of uname -a,

I forget those details of uname output. But I do recall that it is typical for 32 bit kernels.

Quote:

or simply i should understand that as it does not contains x86_64(as it is) kernel installed is 32 bit.

Your kernel is 32 bit.

abhishekrahel · 05-18-2008, 05:08 PM

Quote:

Originally Posted by johnsfine

Correct.

I did a couple searches to try to find the meaning of LONG_BIT in getconf and failed to find it. Maybe some expert will tell us both.

But I know the meaning of lm in flags. Your CPU is 64 bit.

I forget those details of uname output. But I do recall that it is typical for 32 bit kernels.

Your kernel is 32 bit.

Thanks Johnsfine for your time.This is only 2nd time i posted my doubt here
but no doubt i got a overwhelming response.Really its great to share knowledge and have a healthy discussion.Lets carry on.....again thanks,
Have a good time always...